* mem-stats.h (mem_alloc_description::unregister_descriptor): New
	method.
	(mem_alloc_description::release_object_overhead): Fix comment typos.
	* hash-table.h (hash_table::~hash_table): Call
	release_instance_overhead only if m_entries is non-NULL, otherwise
	call unregister_descriptor.

Co-Authored-By: Jakub Jelinek <jakub@redhat.com>

From-SVN: r269943